Fan assembly and impeller thereof

ABSTRACT

A fan assembly and impeller thereof. The impeller comprises a hub having an upper surface, an axial sidewall extended along the axis of the impeller, and a corner connected between the upper surface and the axial sidewall; and a plurality of blades directly connected to the upper surface, the corner or the axial sidewall of the hub to define an air-intake space between an inner edge of the blades faced to the axis of the impeller and the upper surface of the hub for allowing the intake airflow to radially flow toward the blades.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of co-pending application Ser. No. 10/827,285, filed on Apr. 20, 2004, and for which priority is claimed over Application No. 93102369 filed in Taiwan on Feb. 3, 2004 under 35 U.S.C. § 119; the entire contents of all are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present inventions relates to a fan assembly, and in particular, to a fan and an impeller thereof with higher strength and better performance.

2. Description of the Related Art

Electronic devices generally produce heat during operation, and thus a heat-dissipating device or a fan assembly is required to dissipate the generated heat. Since the demand for heat dissipation has been increased, fans must offer optimal performance. A conventional impeller 10 a of a fan is shown in FIG. 1A, including a plurality of blades 21 and a hub 22. The blades 21 encircle the hub 22. The blades 21 are disposed in a frame 20 and connected to the hub 22 via a connecting portion 24 extending from a bottom of the hub 22. A gap 23 is formed between the hub 22 and the blades 21, and above the connecting portion 24.

As shown in FIG. 1B, airflow enters the gap 23 to contact the blades 21 and flows in a direction shown by the dotted line arrows. Due to space limitations imposed by the other elements in the fan, a conventional way for increasing the rotation speed of the motor is to increase the height H of the motor or the hub to approximately the same height as the blades 21. The motor, however, almost entirely blocks the inlet such that the airflow is unable to smoothly flow through the gap 23 between the blades 21 and the hub 22. Thus, the contact area between the airflow and the blades 21 is insufficient. Because the inlet area is reduced, the performance is also reduced. Furthermore, the conventional fan requires the gap 23, thereby weakening the strength of the impeller.

As mentioned above, the conventional fan needs to increase the height of the motor in order to increase power and rotation speed, but the length of the blades 21 must also be increased to increase the airflow contact area. The longer the blades 21, however, the weaker the strength of the impeller, that is, the long blades 21 are easily deformed.

Another conventional impeller 10 b adds a rib 25 to increase the strength of the blades 21, as shown in FIGS. 2A and 2B. Each blade 21 of the impeller 10 b is divided into upper and lower partial blades 21 a and 21 b. The rib 25 is disposed between the upper and lower partial blades 21 a and 21 b and connected to the hub 22. Thus, the blade structure can be strengthened by the rib 25. The rib 25, however, may interfere with the airflow, which must travel around the rib 25 to enter the gap 23, thus causing turbulence. Furthermore, the amount of inflow is reduced due to insufficient contact area between the airflow and the blade 21. As a result, the motor is unable to increase the rotation speed.

Hence, the above method is still unable to satisfy the demands of both structural stability and fan performance.

SUMMARY OF THE INVENTION

Therefore, an object of the present invention is to provide a fan that eliminates the shortcomings described above.

The present invention provides an impeller comprising a hub having an upper surface, an axial sidewall extended along the axis of the impeller, and a corner connected between the upper surface and the axial sidewall; and a plurality of blades directly connected to the upper surface, the corner or the axial sidewall of the hub to define an air-intake space between inner edges of the blades faced to the axis of the impeller and the upper surface of the hub for allowing an intake airflow to radially flow toward the blades.

Preferably, the blades are arranged as an annular structure having an outer diameter greater than that of the hub, and an inner diameter less than or equal to the outer diameter of the hub, wherein each blade is only directly connected to the axial sidewall of the hub, or each blade is directly connected to the upper surface, the corner and the axial sidewall of the hub.

Preferably, each of the blades has a bottom end extending downward along the axial sidewall and there is height difference between the bottom end of the blade and a lower end of the hub.

Preferably, the blades are radially extended and has an outer edge protruded out from the corner of the hub.

Alternatively, the blades are arranged as an annular structure having an outer diameter equal to or less than that of the hub, wherein each blade is only directly connected to the upper surface and the corner of the hub and has an outer edge aligned with the axial sidewall of the hub, or each blade is only directly connected to the upper surface of the hub.

In addition, the impeller further comprises an ring formed on an outer top corner of the blades to connect the blades, wherein a periphery of the ring is aligned with outer edges of the blades.

Preferably, the hub and the blades are integrally formed as a single unit.

Another object of the present invention is to provide a fan assembly comprising an impeller comprising a hub having an upper surface, an axial sidewall extended along the axis of the impeller, and a corner connected between the upper surface and the axial sidewall; and a plurality of blades directly connected to the upper surface, the corner or the axial sidewall of the hub to define an air-intake space between inner edges of the blades faced to the axis of the impeller and the upper surface of the hub for allowing an intake airflow to radially flow toward the blades; and a motor mounted within the hub of the impeller for driving the impeller to rotate.

Preferably, the fan assembly further comprises an ring formed on an outer top corner of the blades to connect the blades, wherein a periphery of the ring is aligned with outer edges of the blades, wherein the hub, the blades and the ring are integrally formed as a single unit.

In addition, the fan assembly further comprises a frame for receiving the impeller and the motor therein. When the impeller is driven by the motor to rotate, an airflow is axially suck and axially flow out of the frame.

Alternatively, when the impeller is driven by the motor to rotate, an airflow is axially suck and radially flow out.

DESCRIPTION OF THE DRAWINGS

The present invention can be more fully understood by reading the subsequent detailed description in conjunction with the examples and references made to the accompanying drawings, wherein:

FIG. 1A is a schematic diagram of a conventional impeller;

FIG. 1B is a cross section of a conventional fan having the impeller shown in FIG. 1A;

FIG. 2A is a schematic diagram of another conventional impeller;

FIG. 2B is a cross section of another conventional fan having the impeller shown in FIG. 2A;

FIG. 3A is a schematic diagram of a fan assembly of a first embodiment;

FIG. 3B is a perspective diagram of an impeller of the first embodiment shown in FIG. 3A;

FIG. 3C is a cross section viewed along line AA, of FIG. 3B;

FIG. 4 is a schematic diagram of an impeller of the second embodiment according to the present invention;

FIG. 5 is a schematic diagram of an impeller of the third embodiment according to the present invention;

FIG. 6A is a schematic diagram of an impeller of the fourth embodiment according to the present invention;

FIG. GB is a cross section along line BB′ of FIG. 6A;

FIG. 7 is a cross section of an impeller of the fifth embodiment according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION First Embodiment

FIG. 3A is a schematic diagram of a fan assembly 3 of the first embodiment. FIGS. 3B and 3C are schematic diagrams of an impeller 30 of the first embodiment shown in FIG. 3A. The fan assembly 3 comprises a frame 36, a motor 35, and an impeller 30. The impeller 30 is disposed in the frame 36 and comprises a hub 32 and a plurality of blades 31. The hub 32 includes an upper surface 321, a lower surface 323, an axial sidewall 322 extended along the axis of the impeller 30, and a corner 324 connected between the upper surface 321 and the axial sidewall 322. The motor 35 is completely mounted within the hub 32 as shown in FIGS. 3A and 3C. The blades 31 are directly connected to the axial sidewall 322 and the corner 324, and arranged as an annular structure. The blades 31 and the hub 32 can be integrally formed as a single unit, and there is no gap therebetween. As a result, the strength of the impeller 30 is improved to prevent blade deformation and warping.

Furthermore, in the present invention, the motor 35 is redesigned to match the size of the hub to be completely disposed within the hub in order to increase air inflow. Unlike the conventional motor with a thick and compact profile, the present invention reduces the height H of the motor 35 and increases its width. Thus, the motor 35 is wide and thin. Although the size is changed, the performance and power of the motor is preserved.

As shown in FIG. 3C, the blades 31 are arranged as an annular structure having an outer diameter D₁. The outer diameter D₁ is greater than the outer diameter L of the hub 32. In addition, the inner diameter d of the annular structure is less than the outer diameter L of the hub 32.

An upper end 31 a of the blade 31 is positioned higher than the upper surface 321 of the hub so that there is an air-intake space is formed between the inner edge 31 c of the blades 31 and the upper surface 321 of the hub 32 for allowing the intake airflow to radially flow toward the blades as the dotted line arrows shown in FIG. 3C.

Each blade 31 of the impeller 30 has a bottom end 31 b extending downward along the axial sidewall 322. There is a height difference h between the bottom end 31 b of the blade 31 and the lower end 323 of the hub 32. The axially extended bottom end 31 b increases the total length of each blade 31, thereby increasing the strength thereof.

In addition, the impeller 30 further comprises a ring 33 formed on the outer top corner of the blades 31 to connect all blades as shown in FIGS. 3B and 3C. A periphery of the ring is aligned with outer edges of the blades 31. The blades 31, the ring 33 and the hub 32 can be integrally formed as a single unit

Second Embodiment

FIG. 4 shows an impeller 30 a of the second embodiment. The impeller 40 is similar to the first embodiment except that there is no frame and the blades 31 of the impeller 30 a are arranged as an annular structure with an outer diameter D₁ greater than the outer diameter L of the hub 32, and an inner diameter d equal to the outer diameter L of the hub 32. That is, the blade 31 is only directly connected to the axial sidewall 322 of the hub 32. Thus, this embodiment can utilize a motor with a larger diameter L. Accordingly, the blades 31 are axially extended along the sidewall 322, wherein the upper ends of the blade 31 is positioned higher than the upper surface 321 of the hub so that there is an air-intake space is formed between the blades 31 and the upper surface 321 of the hub 32 for allowing the intake airflow to axially flow in and radially flow out through the blades as the dotted line arrows shown in FIG. 4.

Third Embodiment

FIG. 5 shows an impeller 30 b of the third embodiment. The impeller 30 b is similar to the second embodiment except that the blades 31 of the impeller 30 b are arranged as an annular structure with an outer diameter D₁ greater than the outer diameter L of the hub 32, and an inner diameter d less than the outer diameter L of the hub 32. Thus, the blades 31 are only directly connected to the upper surface 321 and the corner 324 of the hub 32. Furthermore, the blades 31 of this embodiment are radially extended and an outer edge 31 d of the blade is protruded out from the corner 324 so that the blades are wider than those of the above-described embodiments. Namely, compared to the above-described embodiments, this embodiment can utilize a motor with smaller diameter L.

Additionally, although the size of the motor or the connection between the blades 31 and the hub 32 varies, the inlet area remains constant. Thus, the performance of the fan is greatly improved.

Fourth Embodiment

FIG. 6A is a schematic diagram of an impeller 30 c of the fourth embodiment. FIG. 6B is a cross section viewed along line BB′ of FIG. 6A. The impeller 30 c is similar to the third embodiment except that the blades 31 are formed into an annular structure with an outer diameter D₁ equal to the outer diameter L of the hub 32. Thus, as shown in FIGS. 6A and 6B, each blade 31 is only directly connected to the upper surface 322 and the corner 324 of the hub 32 and the outer edge 31 d is aligned with the axial sidewall 322. The inlet area remains unchanged. Thus, the present invention can be utilized in a fan with a motor of any diameter L.

Fifth Embodiment

FIG. 7 is a cross section of an impeller 30 d of the fifth embodiment. The impeller 30 d is similar to the fourth embodiment except that the blades 31 are arranged as an annular structure with an outer diameter D₁ smaller than the outer diameter L of the hub 32. Each blade 31 is disposed on and only connected to the upper surface 321 of the hub 32. The inlet area remains the same as the above embodiments, and thus, the present invention can be utilized in a fan with a motor of any diameter L.

In conclusion, the present invention has blades directly connected to the upper surface, the corner or the axial sidewall of the hub. No gap is formed between the blades and the hub. Instead, an open space is surrounded by the blades and above the hub. Thus, the strength of the impeller is improved without sacrificing the inlet area size. Additionally, instead of using a thick motor, a thin and wide motor with the same power and performance is used for the impeller according to the present invention. Thus, the impeller of the present invention not only has greater strength but also provides larger air inflow to increase rotational speed and provide better performance.

Finally, while the invention has been described by way of example and in terms of the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. On the contrary, it is intended to cover various modifications and similar arrangements as would be apparent to those skilled in the art. Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements. 

1. An impeller comprising: a hub having an upper surface, an axial sidewall extended along the axis of the impeller, and a corner connected between the upper surface and the axial sidewall; and a plurality of blades directly connected to the upper surface, the corner or the axial sidewall of the hub to define an air-intake space between inner edges of the blades faced to the axis of the impeller and the upper surface of the hub for allowing an intake airflow to radially flow toward the blades.
 2. The impeller as claimed in claim 1, wherein the blades are arranged as an annular structure having an outer diameter greater than that of the hub, and an inner diameter less than or equal to the outer diameter of the hub.
 3. The impeller as claimed in claim 1, wherein each of the blades has a bottom end extending downward along the axial sidewall and there is height difference between the bottom end of the blade and a lower end of the hub.
 4. The impeller as claimed in claim 1, wherein the blades are radially extended and has an outer edge protruded out from the corner of the hub.
 5. The impeller as claimed in claim 1, wherein the blades are arranged as an annular structure having an outer diameter equal to or less than that of the hub.
 6. The impeller as claimed in claim 1, wherein each blade is only directly connected to the upper surface and the corner of the hub and has an outer edge aligned with the axial sidewall of the hub.
 7. The impeller as claimed in claim 1, wherein each blade is only directly connected to the upper surface of the hub.
 8. The impeller as claimed in claim 1, wherein each blade is only directly connected to the upper surface and the corner of the hub.
 9. The impeller as claimed in claim 1, wherein each blade is only directly connected to the axial sidewall of the hub.
 10. The impeller as claimed in claim 1, wherein each blade is directly connected to the upper surface, the corner and the axial sidewall of the hub.
 11. The impeller as claimed in claim 1, further comprising an ring formed on an outer top corner of the blades to connect the blades, wherein a periphery of the ring is aligned with outer edges of the blades.
 12. The impeller as claimed in claim 1, wherein the hub and the blades are integrally formed as a single unit.
 13. A fan assembly comprising: an impeller comprising: a hub having an upper surface, an axial sidewall extended along the axis of the impeller, and a corner connected between the upper surface and the axial sidewall; and a plurality of blades directly connected to the upper surface, the corner or the axial sidewall of the hub to define an air-intake space between inner edges of the blades faced to the axis of the impeller and the upper surface of the hub for allowing an intake airflow to radially flow toward the blades; and a motor mounted within the hub of the impeller for driving the impeller to rotate.
 14. The fan assembly as claimed in claim 13, wherein the blades are arranged as an annular structure having an outer diameter greater than that of the hub, and an inner diameter less than or equal to the outer diameter of the hub.
 15. The fan assembly as claimed in claim 13, wherein each of the blades has a bottom end extending downward along the axial sidewall and there is height difference between the bottom end of the blade and a lower end of the hub.
 16. The fan assembly as claimed in claim 13, wherein the blades are radially extended and has an outer edge protruded out from the corner of the hub.
 17. The fan assembly as claimed in claim 13, wherein the blades are arranged as an annular structure having an outer diameter equal to or less than that of the hub.
 18. The fan assembly as claimed in claim 13, further comprising an ring formed on an outer top corner of the blades to connect the blades, wherein a periphery of the ring is aligned with outer edges of the blades.
 19. The fan assembly as claimed in claim 18, wherein the hub, the blades and the ring are integrally formed as a single unit.
 20. The fan assembly as claimed in claim 13, further comprising a frame for receiving the impeller and the motor therein.
 21. The fan assembly as claimed in claim 20, wherein when the impeller is driven by the motor to rotate, an airflow is axially suck and axially flow out of the frame.
 22. The fan assembly as claimed in claim 13, wherein when the impeller is driven by the motor to rotate, an airflow is axially suck and radially flow out. 